Rainwater Harvesting


What is rainwater harvesting and why is it Important?
Water is our most precious natural resource and something that most of us take for granted. We are now increasingly becoming aware of the importance of water to our survival and its limited supply, especially in times of drought in San Antonio when the Aquifer gets low. The harvesting of rainwater simply involves the collection of water from surfaces on which rain falls, and subsequently storing this water for later use. Normally water is collected from the roof(s) and stored in rainwater tanks.


Rainwater Harvesting Techniques
All that is necessary to capture this water is to direct the flow of rainwater from roof gutters to a rainwater storage tank. By doing this, water can be collected and used for various uses.


If you are reliant on collected rainwater and are not connected to a towns water supply, then the water collected will be especially important to you. If you are from the city, then it is possible to replace all or at least a substantial portion of your fresh water requirements by the capture and storage of rainwater from your roof. Being largely self sufficient in water supply is possible for a vast majority of San Antonio & Hill country households and buildings.


What are the Benefits in Rainwater Harvesting?
By capturing water directly, we can significantly reduce our reliance on the Aquifer. Collecting and using your own water can also significantly reduce your water bills. By capturing water, the flow of stormwater is also reduced and this minimises the likelihood of overloading the stormwater systems in our neighbourhoods.


Commonly Asked Questions


Isn’t Rainwater Harvesting more expensive than a using a Well?
Not really. The installation cost is comparable & rainwater harvesting will save you money on filters. Unlike well water, rainwater harvesting does not require a water softener. The filtration of well water can be costly while rainwater harvesting filtration is rather inexpensive. With the “first flush”, the majority of dust and debris is automatically filtered out. Then, a cloth filter hanging above the water level inside the top of the tank will catch any additional debris. This filter is washable and usually only needs rinsing once every 6 months. As the water leaves the tank to become potable water in your faucet, 3 stages of filtration occur. Stage 1 is a 10 Micron Filter; Stage 2 is a 2 Micron Filter. Both filters are only about $40 each and require replacement about every 6 months. The 3rd Stage of filtration is an inexpensive UV Light that only needs replacing about once a year. Most people can change the filters on their on rainwater harvesting system in about 15 minutes. People usually comment how much better the rainwater tastes than well water.


What About Dirty Roofs?
There are a number of devices (first flush devices) which allow for the first flow of water to the rainwater storage tank to be diverted from the tank. By doing this, any dirt on the roofs of buildings that has built up prior to the rain can be excluded from the tank.


What happens if I run out of water?
The advantage of rainwater harvesting over well water is that rainwater harvesting tanks has a water level indicator and a well does not. You will always know how much water is in your tank whereas with a well you have no way of knowing if it is about to run dry. There are a number of readily available sources to have potable water delivered in about 12 hours, at a very inexpensive rate. Whereas drilling deeper in a well or digging a new well can take weeks and cost thousands of dollars.

Note: Even when it’s not raining, condensation can gather on a metal roof and be harvested in your tank.


How much rain does it take to fill a rainwater harvesting tank?
Depending on your roof size, 1 rain event has been shown to harvest up to 8,000 gallons of water.

Custom Homes Helping Hands Program

Steve Sierleja, while living environmentally conscious himself, advocates a mantra in all of his company practices for Custom Homes LTD and BuildBlock of South Central Texas… “Green Building practices need to be the norm not the exception. We need to be good Stewards of this Earth for future generations. We have the capabilities presently to improve this world for all.”

Member - National Association of Home BuildersMember - Hill Country Home Builders AssociationEqual Housing - HUDEnergy StarSmart Energy BuilderICF - Insulating Concrete Forms - BuildBlock